1. Field of the Invention
The present invention relates to a method and a device for cooling a mass of a, for example, meat-, tissue-, vegetable- and/or fruit-containing substance in a container, in particular a mixer, blender or mill, using liquefied nitrogen (N2) which is supplied in the lower region of the container at a constant working pressure via at least one nozzle.
2. Related Art
Generic methods and devices are known, for example, from EP 0 978 697 A1 or WO 98/57196 which likewise deal with the known problem that sometimes tough foodstuffs, such as meat-, tissue-, vegetable-, and/or fruit-containing products, often cause clogging in devices, such as mixers, blenders or mills, and are difficult to process any further. In this respect, it is known to make the mass brittle, for example by cooling with liquid nitrogen, so that clogging is reduced and further processing, for example into hamburgers, chicken nuggets, vegetable burgers, fruit pouches or the like, becomes easier.
The mass is preferably cooled with liquid nitrogen by uniform penetration. For this purpose, rotating blade elements are arranged in the container, which mix, blend, knead and/or grind the mass of a substance. Liquefied nitrogen is simultaneously supplied in the lower region of the container at a constant working pressure via at least one nozzle. Depending on the substance to be mixed, after about 2 to 60 minutes the mass acquires a consistency which allows easier further processing.
However, cooling processes of this kind have not always proceeded reliably in the past. Thus, it was to be observed that the nozzles projecting in the lower region of the container repeatedly become blocked and/or iced up individually. As a result of the impaired supply of liquid nitrogen, the duration of the cooling process became up to 50% longer in a disadvantageous way. Moreover, the nozzles had to undergo cleaning, and this was possible usually only in stoppage times and after a sometimes complicated conversion of the plant.
The object of the present invention is to specify a method and a device which ensure reliable operation for cooling a mass of a substance. In particular, simple cleaning of nozzles, even within the duration of a cooling process, is to become possible.